Art of making electrolytic iron



F. A. EUSTIS, C. R. HAYWARD, H. M. SCHLEICHER, AND D. BELCHER.

ART OF MAKING ELECTROLYTIC IRON. APPLICATION FILED JAN. 17, 1922.

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FREDERIC A. E'U'STIS, OF MILTON, CABLE R. HAYWARD, 01E QUINCY, AND HENRY1h SCHIIEICHER AND DONALD BELCHER,

OF BOSTON, MASSACHUSETTS, ASSIGNORS,

BY DIRECT AND MESN'E ASSIGNMENTS, OFONE-HALF T SAID EUSTIS AND ONE HALET0 CHARLES PAGE PEBIN, OF NEW YORK, N.. Y. A

AM or MAKING nrncrnorxrrro mom.

Original application filed December 1, 1920, Serial No. 427,541. Dividedand this application filed Jannary 17, 1922. Serial No. 529,859.

- To all it may concern Be it known that we, FREDERIC A. EUSTIS, ofMilton, CABLE R. HAYWARD, of Qunicy, both in, the county of Norfolk,HENRY M. 5 SoHLmoHER and DONALD BELOHER, of Boston, in the count ofSuffolk, all in the Commonwealth of if of the United States, haveinvented new and useful Improvements in the Art of Making ElectrolyticIron, of which the following is a specification.

This invention relates to the manufacture of electrolytic iron fromsolutions,'and particularly to the preparation of the ferrous solutionfrom oxides of iron for the electrolytic deposit of iron.

The present application is a division of an application filed by usDecember 1, 1920, Serial No. 427,541. now Letters Patent of the UnitedStates No. 1,412,174, dated April 11,1922, and is addressed particularlyto that modification of the invention described in our said formerapplication adapted for the treatment of 'oxidized ores of iron, orother oxides of iron.

It has heretofore been considered that oxides of irofi were racticallyinsoluble, and so far as we are aware they are insoluble by any processheretofore known. Therefore oxidized ores of iron, and other sources offerric oxide, have not been considered practicable sources of supply forthe manufacture of electrolytic iron by dissolving iron to form aferrous solution and thereafter 85 depositing iron from the solution'bythe action of electrolysis.

We have discovered that oxides of iron may be dissovled from oxidizedores of iron or other similar source by means of a sol- 40 ventcontaining dilute acid and suitable quantities of ferrous salts. Forexample a solution containing dilute hydrochloric acid and a generousquantity of ferrous chloride, or a solution containlng dilute sulphuricacid and a generous quantity of ferrous sulphate, will act as a solventof oxides of iron and after reduction form a ferrous solutionsuitablefor the electrolytic deposit of iron.

For a detailed description of our processv to as a whole reference ismade to our said A Patent No. 1,412,174. The invention form?assachusetts, all citizens ing the subject-matter. of the presentapplication has to do primarily with the use of ferric oxide as thesource of iron and we will therefore describe herein only suchfeaturesof the general process as are necessary to make clear itsapplicability to the treatment of oxides of non. The oxide of iron usedas the source of iron in the present process is preferably in the formof an OK- idized ore of iron such as limonite hematite or magnetite.

The ferrous solution from which iron is deposited by electrolysis may bea solution of ferrous chloride in water, a ferrous sulphate solution, orindeed a solution containing any salts of iron that will in solutiondissociate to deposit iron under the action of electrolysis, that willform the two series of salts, ferric and ferrous, and that will attackthe ore or other raw material constituting the source of iron.

The ferrous solution when made by the method hereinafter described willcontain at least some acid or ferric salts, such as ferric chloride,-although it may be only traces, and must be thorougly neutralized beforeit is suitable for the production of electrolytic iron, because thepresence of acid or ferric salts causes a poor iron deposit and resultsin low current efficiency To this end the solution is mixed withpulverized limestone in a suitable tank. Limestone furnishes calciumcarbonate (CaCO which is the most suitable agent for neutralization, asit 'has the capacity of readily precipitating first ferric salts beforeprecipitating the ferrous salts. We have found that for the best resultsit is advisable to use enough neutralizing agent to precipitate a smallamount of ferrous iron. This insures complete neutralization of theliquor, the neutrality of the solution in the cathode compartment of theelectrolytic cell being an indis ensible condition for the most'efiicient e ectrolysis of iron. I

The solution is then filtered if necessary, heated nearly to the boilingpoint, and passed hot into the cathode com artment of a diaphragmelectrolytic cell. Uiider proper conditions metallic iron is depositedon the cathode. The l quor p sses through the dia (or sulphate) phragminto the anode compartment and is thence returned to the process to beused in making more ferrous solution as hereinafter described.

A special electrolysis cell A is used for depositing the iron, of thekind fully de-- scribed in our said former patent to which reference ismade for a more detailed description of its construction and mode of.operation.

The accompanying drawings indicate diagrammatically apparatus forperforming the process, illustrating in two alternative forms the cyclesof operations.

Referring first to Fig. 1, the anode liquor containing ferric chlorideand ferrous chloride, (or ferric and ferrous sulphates if the originalsolution was a sulphate instead of a chloride) should first be reducedto a ferrous solution. The hot anode liquor is discharged from the anodecompartment of electroiytic cell A into the top of a reducing towerpacked with coke. A gas containing sulphur dioxide (S0 is introduced atthe bottom of the tower and rising through the tower comes into contactwith the descending solution. This reduces the ferric chloride (orsulphate) to ferrous chloride and the resulting liquor discharged fromthe reducing tower contains a large amount of ferrous chloride (orsulphate), a small amount of sulphuric acid and a small amount ofhydrochloric acid. This constitutes a leach liquor by which the oxidesof iron may be dissolved from the oxidized ore. This liquor possesses apeculiar ability with great rapidity and substantial completeness todissolve the relatively insoluble ferric oxides. The reduced leachliquor is then put on the ore in a solution tank B where it dissolvesiron from the ore, and is then filtered at C. Thence the major part ofthe solution is pumped back to the top of the reducing tower, whileoptionally the smaller part will be advanced to limestone tower D forneutralizing and there-' after electrolyzing at A as before. The partwhich is sent to the limestone tower may be passed through scrap iron ina tank F for the purpose of further enriching the solution in iron andat the same tlme using up part of the acid coming from the solution tankB.

As an alternative method of reducing the anode liquor, it may bedelivered from the main electrolysis tank A in which the iron isdeposited, into a second electrolytic cell G (see Fig. 2) which may betermed an electrolytic reducing cell. The application of electric energyto the ferric solution in the electrolytic reducing cell G will reducethe solution from the ferric to ferrous state. This reduction of theferric salts formed in the electrolysis cell A furnishes acid needed fordissolving the oxidized ore. In QthQ indicated in Fig. 1.

The reason for returning the greater part of the liquor from the oresolution tank to the reducing tower or the reducing cell as the case maybe, is that the eflect of the action of the leach liquor on mostoxidized ores isto take some of its iron into solution in ferric state;therefore, the solution coming from the ore solution tank will containferric salts and must again be reduced.

If all the liquor were sent direct to the limestone neutralizing tank itwould be necessary to use large amounts of limestone for neutralizationbecause of the large amount of ferric chloride present in the solutiondissolved from the ore. This is not only costly in limestone but may-useup too much acid in the neutralization step. Therefore, a part of thesolution is sent from the ore solution tank back to the reducing cellwhere the ferric chloride dissolved from the ores is reduced, and thesolution so reduced upon again passing over the ore picks up more ferriciron but only one-third as much as was present immediately before it wasreduced. Thus by repeatedly cycling part of the solution through thereducing tower and over the ore the ferric iron in that .part of thesolution advanced "to the limestone tank may be diminished to any pointdesired.

Since sulphur dioxide is not usedfor reduction in the 2, but merelyelectrical energy, there is no source of new acid in the. cyclic processitself and the acid must therefore be carefully conserved. This can bedone by turning a large portion of the solution from the ore solutiontank back to the reducing cell and advancing only a small portion to thelimestone tank for neutralizing. Even with this mode there is some lossof acid which can economically be restored by blowing S0 gas into theliquor in the reducing cell or at some other convenient point. When thereduction of the anode liquor is performed by an electrolytic reducingcell, oxygen comes off at the anode ofthe reducing cell during theelectrolysis if a sulphate electrolyte is used, and may be'recovered asa by-product. When a chloride electrolyte is used chlorine gas is givenoff and for this reason the electrolytic method of reduction is lessdesirable for chloride solutions than fon sulphate solutions.

The ore to be treated in the solution tank procedure indicated in Fig.

B should be finely ground or pulverized tonaeaeee results may beobtained at a temperature of 70 C. and above. It is also desirable tostir or agitate the mixture in order to insure constant contact ofactive solvent with the ore; or percolation may be used. Acountercurr'ent method of leaching is advised, by which fresh ore istreated with the weakest solution and the residue of the ore is treatedwith fresh solution. C

It will be understood as already indicated that the procedure isessentially the same whetherthe solutions used are chloride or sulphatesolutions.

We claim:

1. The art of makin a ferrous solution, suitable for the electro yticdeposit of iron, which comprises the step of dissolving oxide of iron ina solvent containing dilute acid and a ferrous salt.

2. The art of making a ferrous solution, suitable for the electrolyticdeposit of iron,

. which comprises reduclng a solution containing ferric salts to producea solvent of oxides of iron, and dissolving'oxide of iron in saidsolvent.

3. The art of making a ferrous solution, suitable" for the electrolyticdeposit of iron, which comprises reduclng a solution containing ferricsalts by means adapted to produce a solvent of oxides of iron consistingof a solution containing ferrous salts and dilute acid, and dissolvingoxide of iron in said solvent.

4. The art of making a ferrous solution, suitable for the electrolyticdeposit of iron,

, which comprises reducing a solution containing ferric salts by meansof sulphur dioxide to form a solvent of oxides of iron consisting of asolution containing ferrous salts and dilute sulphuric acid, anddissolving oxide of iron in said solvent.

5. The art of making a ferrous solution, su table for the electrolyticdeposit of iron, I

which comprises the step of dissolving oxide of iron 1n a solventcontaining dilute sulphuric acid and ferrous sulphate.

6. The art of making electrolytic iron which comprises reducing a.solution con-1 taining ferric salts by means adapted to pro-.

which comprises reducing a ferric sulphate solution by means adapted toproduce a solvent of oxides of iron consisting of a solution containingdilute sulphuric. acid and ferrous sulphate and dissolving oxide of ironin said solvent.

8. The art of making electrolytic iron which comprises reducing asolution containing ferric salts by means adapted to produce a solventof oxides of iron consisting of a solution containing ferrous salts anddilute acid, dissolving oxide of iron in said solvent, depositing ironfrom said solvent by electrolysis leaving a ferric solution suitable forreduction according to the first :Step hereinbefore specified in orderto be again made into a solvent, thus completing the cycle.

9. The art of making electrolytic iron which comprises reducing asolution containing ferric salts by means adapted to produce a solventof oxides .of iron consisting of a solution containing dilute acid and aferrous salt, dissolving 1ron in said solvent, dividing the resultantiron solution so formed, returning part thereof to the ferric solutionat the reducing step for repeated reduction, and advancing part onlythereof for the deposition of iron by electrolysis.

Signed by us this 9th day of January, 1922. w

' FREDERTG A. EUSTIS.

. CABLE R. HAYWARD.

' HENRY M. SCHLETCHER. DONALD BELCHER.

